BriansRanLogbook

This is where I write down what I'm doing

1/13/23 : Turned on HpGe HV to 1500 and learned about analog to digital signal processing

detected signal rate -vs- HpGe Voltage

HpGe Detector

HPGe Counts vs Voltage Cs-137 Source

High Voltage (V)	Counts (with source)	Counts (no source)
1492.67	1532.5 ± 36.67	167.5 ± 7.78
799.15	1336.5 ± 2.12	149.4 ± 34.65
396.83	1193.5 ± 54.48	127.5 ± 7.78
197.19	1035.5 ± 40.31	121 ± 4.24
4.88	562.5 ± 2.12	332 ± 35.36

05/02/2023 Amplifier Course Gain: 2 High Voltage: 1500V

run 7343 Disc Thresh:0.588V

run 7345 Disc Thresh: 0.500V

run 7346,7347 Disc Thresh: 0.425V

Background Subtracted graph for Cs-137

run 7348, Disc Thresh: 0.351V

run 7351, Cs-137 source, Disc Thresh: 0.306V run 7353, EU-152 source Disc Thresh: 0.306V

He3 Tube

1/27/23 : Turned on He3 detector, adjusted to find counts with Cf source in containment and out of containment

2/3/23 : Same as 1/27, adjusting discriminator voltage and recording counts with Cf-252 source. Encountered strange effects of higher counts with source away at low QD voltage. Sets of measurements notably inconsistent.

He3 Counts vs Voltage (1208 HV)

Discriminator Voltage (V)	Counts/10s (no source)	Counts/10s (with source)
2.003	4.4 ± 1.67	97.0 ± 8.49
1.788	4.8 ± 1.09	108.2 ± 10.89
1.503	5.4 ± 2.22	105.7 ± 8.63
1.227	7.9 ± 3.14	109.8 ± 9.34
1.009	89.9 ± 7.87	234.1 ± 20.06
0.799	2656 ± 251.1	2447 ± 183.0
0.485	55479 ± 1325	48360 ± 1938

Plateau graph for He3 tube at 1208V

2/10/23 Same procedure as 2/3/23, just changing HV applied to He3 detector to values of 1300V then 1100V.

He3 Counts vs Voltage (1100 HV)

Discriminator Voltage (V)	Counts/10s (no source)	Counts/10s (with source)
1.971	4.6 ± 2.37	107.7 ± 13.17
1.775	7.7 ± 2.11	100 ± 10.70
1.486	5.5 ± 2.32	104.8 ± 12.79
1.248	4.7 ± 2.00	99.6 ± 7.09
1.013	75.2 ± 12.17	171 ± 12.82
0.762	3074 ± 143.0	2833 ± 894.7
0.509	19658 ± 424.6	40290 ± 2402

Plateau graph for He3 tube at 1100V

He3 Counts vs Voltage (1300 HV)

Discriminator Voltage (V)	Counts/10s (no source)	Counts/10s (with source)
1.971	5.4 ± 1.78	111.3 ± 9.97
1.773	5.3 ± 1.89	97.3 ± 7.70
1.524	7.1 ± 4.51	99.7 ± 11.78
1.275	12.2 ± 3.55	117.3 ± 23.11
0.993	177.7 ± 8.18	351.9 ± 28.71
0.784	2691.2 ± 114.7	2763.7 ± 126.2
0.485	50346 ± 3831	53920 ± 4354

Plateau graph for He3 tube at 1300V

03/31/2023

• Analyzed the plateau graphs.
• Began taking plateau measurements between a discriminator voltage range of about 1.000V and 1.250V to determine where the noise is cut from the signal.
• Got abnormal fluctuations in counts.

Compton_Michelle.txt

04/04/2023

• Worked with Dr. Forest to tune the He3 detector such that the peak height of the signal could be read by the computer.
• Set up the computer to read from the peak sensing ADC and start taking measurements.
• Started a background measurement to run overnight.

04/05/2023

• Ended the background measurement.
• Took a new measurement, this time with source out.

04/07/2023

• Worked with Dr. Forest to graph the two measurements and to create a graph of the source out measurement minus the background measurement.
• Began re-tuning the detector in order to repeat the process once more.

04/11/2023

• Finished tuning the detector and took another source out measurement. The discriminator threshold this time was at 3.660V.
• Completed a second background measurement.

04/12/2023

• Started a new plateau measurement by taking a measurement with the source out and viewing the graph in root.
• Since the He3 detector was readjusted the new point where noise is cut from the signal has shifted, after some measurements it was determined to now be somewhere between 1.900 and 2.000 instead of the window from 03/31/2023.
• Took a source out measurement at a discriminator threshold 1.900V.

04/18/2023

• Before starting measurements the GUI displayed an error "Lost Connection to the Platform." Had to restart the process.
• After adjusting the discriminator threshold to 1.927V and taking a source out measurement, the data file produced no results when graphing the data in ROOT. Was unable to determine the reason for this. It's possible the width of the logic pulse was accidentally adjusted while while changing the disc voltage or that some adjustment was made to their position so that the computer does not have enough time to read out the measurement. Will check the detector is correctly adjusted and ask Dr. Forest when he returns if that is not the problem.

04/19/2023

• Was unable to determine the reason that the data file was reading out incorrectly. Will have to wait for Dr. Forest to help understand and fix the problem.
• Attempted to start creating background subtracted graphs in ROOT for the measurements already taken.

04/20/2023

• Finished the background subtracted graphs.
• Looked at the peak sensing ADC one more time without success.

• 

  Background subtracted graph for discriminator threshold 3.114V

• 

  Background subtracted graph for discriminator threshold 3.660V

05/08/2023

• Started by doing a coincidence experiment using two plastic scintillators, Jacinda and Michele. We placed the wider one, Jacinda, on a table and connected it to a high voltage power supply at about 1200V as well as the oscilloscope on scope 3.
• Michelle, the thinner scintillator, was connected to another high voltage power supply at about 1050V and connected to scope 4 on the oscilloscope. Both power supplies had negative polarity. Michelle was held above Jacinda and the scope was used to observe coincidence counts. It did appear that we were may have been receiving more pulses through Jacinda that did not pass through Michelle than expected.
• Next, Michelle was connected to a discriminator and sent to a scalar. At the discriminators lowest setting of 0.306V, no counts from background sources were observed. A Cs-137 source was brought close to the scintillator and no counts were observed. We then tried sending Michelle's signal through a spec amp and timing filter amp and then through the discriminator and scalar. Doing this did cause the source in/source out signals to become distinguishable.
• Tried again to send Michelle directly to a discriminator unamplified with a high voltage of 1000V and did observe background counts. The error was likely due to sending the signal through an timing filter amp unnecessarily. The Cs-137 source was brought close to the scintillator again and a noticeable difference in counts between the source in/source out signals was observed.

Source in/source out counts for the Michelle scintillator (1000V)

Source in counts (Hz)	Source out counts (Hz)
112	2
105	2
103	2
122	2
99	3
128	3
98	5
117	4
127	1
117	0
Average: 112 ± 11.15	Average: 2.4 ± 1.43

• Began trying to find the Compton Edge of the Michelle scintillator by turning up the discriminator in intervals of about 0.5 V and measuring the source in/source out counts at each interval until the counts dropped to about zero after subtracting the background
• The discriminator voltages recorded here are the voltages as measured by the multimeter. The discriminator itself has a ten-to-one ratio, thus all recorded voltages should be divided by 10 in order to obtain the true threshold.

Data for the Compton Edge of the Michelle scintillator.

Disc Threshold (V)	Source In (counts/100s)	Source Out (Counts/100s)	Ratio (Source In/Source Out)
0.318 V	10578	271	39.0332
0.354 V	10837	262	41.3626
0.410 V	9908	234	42.3418
0.450 V	9198	213	43.1831
0.503 V	8473	210	40.3476
0.554 V	8152	183	44.5464
0.604 V	7342	154	47.6753
0.653 V	6609	159	41.5660
0.702 V	6076	158	38.4557
0.755 V	5427	139	39.0432
0.805 V	4943	140	35.3071
0.854 V	4500	124	36.2903
0.904 V	3686	130	28.3538
0.950 V	3289	131	25.1068
1.004 V	2533	112	22.6161
1.055 V	2046	126	16.2381
1.104 V	1464	108	13.5556
1.149 V	1148	112	10.2500
1.201 V	825	118	6.9915
1.249 V	553	108	5.1204
1.299 V	385	87	4.4253
1.355 V	230	94	2.4468
1.400 V	210	91	2.3077
1.450 V	135	89	1.5167
1.500 V	111	86	1.2907
1.555 V	109	82	1.3293

Graph of the Compton Edge for the Michelle scintillator

Ratios for the source in/source out counts from the Compton edge data for the Michelle scintillator.

05/09/2023

• Started taking measurements to find the Compton for another unnamed plastic scintillator at a high voltage of 1000V. The unnamed scintillator had a light leak problem so it was not completed.
• Started taking measurements to find the Compton edge of the Ariana scintillator at a high voltage of 1000V.

Compton Edge data for the Ariana scintillator

Disc Thresh (V)	Source In (counts/100s)	Source Out (counts/100s)	Ratio (Source In/Source Out)
0.320 V	9520	229	41.5721
0.352 V	8869	210	42.2333
0.401 V	8016	196	40.8980
0.454 V	7321	185	39.5730
0.508 V	6458	173	37.3295
0.556 V	5712	130	43.9385
0.601 V	4770	156	30.5769
0.658 V	3866	151	25.6026
0.705 V	2860	118	24.2373
0.749 V	2280	127	17.9528
0.803 V	1496	109	13.7248
0.852 V	1036	116	8.9310
0.900 V	690	100	6.900
0.950 V	406	111	3.6576
1.001 V	265	99	2.6768
1.052 V	171	95	1.8000
1.105 V	129	86	1.5000
1.154 V	98	96	1.0208
1.206 V	89	95	0.9368

Compton edge for the Ariana scintillator. The edge appears to be at about 1.125 V

Ratios for the source in/source out counts from the Compton edge data for the Ariana scintillator

Calculation of the Compton Scattering Energies

To equation for Compton scattering is given below

[math]E'_\gamma=\frac{E_\gamma}{1+(E_\gamma/m_ec^2)(1-cos\theta)}[/math]

Where [math]E_\gamma[/math] is the energy of the incoming photon, [math]E'_\gamma[/math] is the energy of the recoiling photon, [math]m_ec^2[/math] is the energy of the electron at rest, and [math]\theta[/math] is the scattering angle. For our Cs-137 source, the energy of the incoming photon is 661.7 keV and the scattering angle is 180°. Thus, we obtain

[math]E'_\gamma=\frac{661.7}{1+(661.7/511)(1-cos(180))}[/math]

[math]E'_\gamma=184.3keV[/math]

By conservation of energy we have

[math]E_\gamma + E_e = E'_\gamma + E'_e[/math]

Since we are assuming the electron is at rest initially, then [math]E_e[/math] will be the rest energy of the electron. To get the momentum energy of the recoiling electron,

[math]E_\gamma - E'_\gamma = E'_e - E_e[/math]

[math]661.7keV - 184.3keV = 477.4keV [/math]

So the momentum energy of the recoiling electron will be [math]477.4 keV[/math].

05/11/2023

• Started a coincidence measurement by placing the active area of Michelle on top of Ariana. The signal for each was sent through a discriminator and then through a dual delay. The delay was adjusted until the pulse from each detector was directly aligned with each other. The pulses were sent through a three fold logic unit on the "and" setting and then the output was sent to a scalar.

The coincidence counts for Ariana/Michelle coincidence detector. Ariana's discriminator threshold was kept at a constant 0.418 V

Michelle Discriminator Threshold (V)	Counts/300s
0.418 V	79
0.454 V	86
0.508 V	86
0.554 V	84
0.598 V	80
0.658 V	90
0.713 V	72
0.754 V	77
0.804 V